(19)
(11) EP 0 439 322 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
01.04.1992 Bulletin 1992/14

(43) Date of publication A2:
31.07.1991 Bulletin 1991/31

(21) Application number: 91300463.6

(22) Date of filing: 22.01.1991
(51) International Patent Classification (IPC)5: G01B 11/14, G03F 9/00, H01L 21/00, G03B 41/00
(84) Designated Contracting States:
DE FR GB NL

(30) Priority: 23.01.1990 JP 13263/90

(71) Applicant: CANON KABUSHIKI KAISHA
Tokyo (JP)

(72) Inventors:
  • Matsusgu, Masakazu
    Ohta-ku, Tokyo (JP)
  • Saitoh, Kenji
    Ohta-ku, Tokyo (JP)

(74) Representative: Beresford, Keith Denis Lewis et al
BERESFORD & Co. 2-5 Warwick Court High Holborn
London WC1R 5DJ
London WC1R 5DJ (GB)


(56) References cited: : 
   
       


    (54) Device and method for measuring the gap between two opposed objects


    (57) A device for detecting relative positional deviation between a mask (2) and a wafer (3) is disclosed, wherein the mask has a first grating pattern and a zone plate pattern and the wafer has a second grating pattern. The device includes a directing system for directing a radiation beam to the first grating pattern of the mask, such that the first grating pattern produces a first transmitted beam which is then inputted to the wafer substantially perpendicularly and a second transmitted beam which is obliquely inputted to the wafer and such that the first grating pattern also produces a first reflected beam; and a detecting system (10) for detecting (i) the first reflected beam and also for detecting (ii) a second reflected beam resulting from reflective diffraction of the first transmitted beam by the second diffraction pattern of the wafer and being displaceable with any inclination of a surface of the wafer and (iii) a third reflected beam resulting from reflection of the second transmitted beam by the wafer surface and from diffraction of the same by the zone plate pattern of the mask and being displaceable with any inclination of the wafer surface and an interval between the mask and the wafer.






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